Rocker arm alignment tool and method

ABSTRACT

An apparatus for and method of aligning rocker arms ( 401  and  403 ) with push rods ( 611 ) during the assembly of an internal combustion engine utilizes an installation tool ( 100 ). The tool ( 100 ) includes a plurality of alignment members ( 101 ) that engage and constrain the rocker arms ( 401  and  403 ) to facilitate installation of the rocker arms ( 401  and  403 ) in alignment with the push rods ( 611 ) during engine assembly.

FIELD OF THE INVENTION

The present invention relates to the assembly of internal combustionengines including, but not limited to, a tool for use in aligning rockerarms during engine assembly.

BACKGROUND OF INVENTION

Rocker arms are often employed in internal combustion engines. Rockerarms control the opening and closing of combustion chamber intake andoutlet valves, and are typically driven by push rods. The rocker armsare typically mounted on a rocker arm carrier, an engine sub-assemblythat attaches to the cylinder head or cylinder block. The rocker armsand other engine components, such as an oil rail, are installed on therocker arm carrier before the carrier is bolted to the cylinder block.Rocker arms may be installed, for example, on ball bearing fulcrums thatallow movement of the rocker arm in multiple directions. Proper engineassembly requires alignment of the rocker arms and push rods.

Because rocker arms move, rocker arms may become misaligned relative tothe push rods during engine assembly. A misalignment, if not found, maycause an engine to run poorly or not run at all. For an assembledengine, discovery and repair of a misaligned rocker arm requiressubstantial engine disassembly and reassembly. Such a repair is timeconsuming and costly.

Accordingly, there is a need to prevent misalignment of rocker armsrelative to push rods during engine assembly.

SUMMARY OF INVENTION

A tool includes a base having a base extension and at least onealignment member attached to the base and having an end. The end iscapable of receiving a rocker arm and limiting movement of the rockerarm during engine assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an isometric view of an alignment tool in accordancewith the invention.

FIG. 2 illustrates a bottom view and FIG. 3 illustrates a top view ofthe alignment tool in accordance with the invention.

FIG. 4 and FIG. 5 illustrate a bottom view of rocker arms engaged withthe alignment members of the alignment tool in accordance with theinvention.

FIG. 6 illustrates a rocker arm carrier with the alignment toolinstalled during engine assembly in accordance with the invention.

FIG. 7 is a flowchart illustrating a method of utilizing the alignmenttool to align rocker arms during assembly of an internal combustionengine in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following describes an apparatus for and method of aligning rockerarms with push rods during the assembly of an internal combustionengine. An alignment tool includes a plurality of alignment members thatengage and constrain rocker arms while permitting desired movement toallowable positions that facilitate installation of the rocker arms inalignment with the push rods during engine assembly.

The alignment tool 100 is shown in FIG. 1. The alignment tool 100includes a plurality of alignment members 101, each having a slot 103,attached to a base 105 of the tool 100. The geometry and orientation ofthe alignment members 101 may be adjusted to accommodate the rockercarrier/cylinder head and rocker arm configuration. Alignment members101 may be connected in pairs to facilitate alignment of intake andexhaust rocker arms for a common cylinder. Alternatively, alignmentmembers 101 may be attached individually to the base 105. Alignmentmembers 101 may be formed in a variety of shapes and thicknessesdepending on the physical dimensions of engine components in proximityto the tool 100 when installed. The alignment members 101 limitundesired rocker arm movement and permit desired rocker arm movement tofacilitate proper alignment of rocker arms with push rods.

The base 105 includes a plurality of projections 107 that extend outwardfrom a side of the base 105. A lower surface of the projections 107, inaddition to other elements from the base 105, form a support surface 109that rests on the carrier during engine assembly. The number, shape, andorientation of the projections 107 may by set based on the position ofbolts or other engine components in the vicinity of the tool 100 wheninstalled on the engine. One or more ribs 111 may be advantageouslyutilized to add rigidity and/or stiffness to a base extension 113 of thealignment tool 100 and to provide a mechanical load path from the baseextension 113 into the projections 107. The ribs 111 may be disposed onone or both sides of the base extension 113. The base extension 113 mayadvantageously have an opening 115 and/or a grip 117 to facilitateholding the tool 100 during installation and removal. The base extension113 may be handheld.

A bottom view of alignment members 101 of the alignment tool 100 isshown in FIG. 2. A slot 103 is shown formed in two of the sides at oneend of each of the alignment members 101. Two surfaces 201 and 203 areshown formed in opposing fingers 207 and 209 of the alignment members101 and function to constrain sideways movement of the rocker arm withinthe alignment member 101. The shape of the slot 103, including theshapes of the surfaces 201 and 203, may advantageously complement thepart of the rocker arm that the tool 100 engages. A third surface 205limits upward rocker arm movement. The slots 103 are advantageouslyformed with two opposing fingers 207 and 209. Alternatively, one or morefingers may be utilized. The end of the alignment members 101 is notlimited to the shape shown in the figures, and may have different types,shapes, and numbers of openings, including channels, holes, grooves, andso forth. A top view of the alignment tool 100 shows the various aspectsof the tool 100.

A bottom view of rocker arms engaged with the alignment members of thealignment tool is shown in FIG. 4 and FIG. 5. An engine may have twotypes of rocker arms. One type of rocker arm 401 may be utilized to openand/or close the exhaust valves and the other type of rocker arm 403 maybe utilized to open and/or close the intake valves.

The general shape of the rocker arms shown is planar with a receptacle501 or 503 on each end. One receptacle 501 engages a push rod while theother receptacle 503 engages a valve stem. The slot 103 in the end ofthe alignment member 101 may advantageously complement the shape of thecorresponding rocker arm 401 or 403. For example, the inner surfaces201, 203, and 205 of the slot 103 form a shape that engages the end ofrocker arm 401 or 403. The rocker arm may alternatively be formed toreceive push rods without receptacles.

The geometry of the various aspects of the tool 100 may vary dependingon the spacing and component clearances of the engine and/or itsassociated rocker arm carrier. The tool may be formed ofinjection-molded plastic. Other materials and formation processes may beutilized to form the tool, which may be a single integral tool or may becomprised of multiple components assembled together.

A rocker arm carrier 601 with the alignment tool 100 installed duringengine assembly is shown in FIG. 6. The rocker arm carrier 601, or otherengine sub-assembly, may be a pre-assembled sub-assembly having aplurality of rocker arms 401 and 403 and other components. A ballbearing 603 is shown attached to a fulcrum plate 605 that is mounted onthe rocker arm carrier 601. The rocker arm 401 operates with the ballbearing 603, which acts like a fulcrum for the rocker arm 401. The ballbearing 603 allows each rocker arm 401 or 403 to move right, left, up,and down. The rocker arm 401 or 403 may move simultaneously in more thanone direction and may tilt sideways to a non-vertical position. Otherengine components, such as an oil rail 607, may be preinstalled on therocker arm carrier 601. As shown in FIG. 6, a valve stem 609 mates withone receptacle 501 of the rocker arm 401 and a push rod mates with theother receptacle 503 during proper installation.

One finger 207 may advantageously be longer than the other finger 209 ofthe alignment member 101. The longer finger 207 is advantageously foundon the side of the rocker arm 401 or 403 opposite the fulcrum plate 605such that the longer finger 207 and the fulcrum plate 605 togetherrestrain rocker arm movement from each side of the rocker arm 401 or403.

In addition, the shape and physical location of other engine components,such as the rocker arm carrier 601 and fulcrum plate 605, as well as therocker arm shape, location, and orientation, may provide some limit torocker arm movement. The rocker arm alignment tool 100 providesadditional limits on rocker arm movement. For example, upward andsideways movement of the rocker arms 401 and 403 is limited when thetool 100 is installed. The tool 100 constrains rocker arm movementwithin desired limits to facilitate alignment with the push rods duringengine assembly without rigidly constraining rocker arms to unmovablepositions.

During engine assembly, the tool 100 is installed such that at leastpart of the support surface 109 rests on the rocker arm carrier 601,cylinder head, or other engine component. The weight of the tool 100 maybe utilized to hold the tool 100 in place on the rocker arm carrier 601,cylinder head, and so forth. Other engine components, such as the oilrail 607, may assist in positioning and/or holding the tool in place.Clips, detents, dowels, and/or other devices may be used to positionand/or retain the tool 100 with respect to the rocker arm carrier 601,cylinder head, or other component as needed and/or desired. When thetool 100 is installed, the alignment members 101 limit movement of therocker arms 401 and 403.

A flowchart illustrating a method of utilizing the alignment tool toalign rocker arms during assembly of an internal combustion engine isshown in FIG. 7. At step 701, a rocker arm alignment tool 100 isinstalled to engage the rocker arms 401 and 403. The rocker arms may bepart of an engine assembly or engine sub-assembly such as the rocker armcarrier 601, cylinder head, and so forth. The rocker arms 401 and 403are inserted into the slots 103 of the alignment members 101 that engageand limit rocker arm movement during installation. For example, thefirst surface 201 and the second surface 203 of each slot 103 may engageand move each rocker arm 401 and 403 sideways into a desired position.Once the tool 100 is installed on each rocker arm 401 and 403, the tool100 rests on the support surface 109 and is supported on the rocker armcarrier 601, cylinder head, or other engine component. Other enginecomponents may be installed before and after the tool 100 is installed.Some components, such as the oil rail 607, may block access to therocker arms 401 and 403, thus installation of the tool 100 beforeinstallation of these components is advantageous.

At step 703, the push rods 611 are engaged with the receptacles 501, orother engagable feature, of the rocker arms 401 and 403. The push rods611 extend from the crankcase or engine block (not shown) below therocker arm carrier 601. Valve stems 609 of either intake or exhaustvalves engage the other receptacles 503 of the rocker arms 401 and 403.The valve stems 609 may be engaged with the rocker arms 401 and 403before the push rods 611 are engaged with the rocker arms 401 and 403 orat the same time the push rods 611 are engaged.

At step 705, the tool 100 is removed from the engine assembly bydisengaging the tool from the rocker arms 401 and 403, leaving the pushrods 611 engaged and aligned with the rocker arms 401 and 403.Advantageously, the tool 100 is removed after the rocker arm carrier 601is secured to the crankcase. The tool 100 may be reused during theassembly of another engine.

Although the present invention is illustrated by the example of a rockerarm alignment tool for use during the assembly of a diesel engine, thepresent invention may be applied to: diesel engines, gasoline engines,or other types of engines; engines having one or more rocker arms;engines having any number of cylinders; various engine types, such asin-line, V type, and so forth; engines having different cylinder firingorders; turbocharged and non-turbocharged engines; and engines of anysize. One or more tools may be utilized to assemble a single engine.

The present invention provides a number of advantages. The toolfacilitates rocker arm alignment with push rods during engine assembly,thereby reducing the likelihood of misaligned push rods that result inpoor or non-existent engine function and require time-consuming andexpensive engine repair. The tool may be used to align rocker arms in arocker arm carrier that is delivered with rocker arms that aremisaligned. The tool advantageously eliminates the need forlabor-intensive manual visual inspections that are increasingly moredifficult to perform on more compact engine designs. Automated visualinspections may not be practical given compact engine designs and thepotential inability to provide automated inspection in today'scomplicated assembly processes. The tool may be fabricated frominexpensive materials. The tool is reusable.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges that come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

1. A tool comprising: a base; and at least one alignment member attachedto the base and having an end, wherein the end is capable of receiving arocker arm and limiting movement of the rocker arm during engineassembly.
 2. The tool of claim 1, further comprising a slot disposed inthe end, wherein the slot is formed to receive the rocker arm and limitmovement of the rocker arm during engine assembly.
 3. The tool of claim1, wherein the end comprises a first finger and a second finger andwherein a slot is formed between the first finger and the second finger.4. The tool of claim 1, wherein the end comprises a first finger and asecond finger and wherein the first finger and the second finger arecapable of limiting movement of the rocker arm between the first fingerand the second finger.
 5. The tool of claim 3, wherein the end comprisesa first finger and a second finger and wherein the first finger iscapable of limiting movement of the rocker arm between the first fingerand a fulcrum plate that supports the rocker arm.
 6. The tool of claim1, wherein a slot comprising a first surface, a second surface, and athird surface is disposed in the end.
 7. The tool of claim 6, whereinthe first surface is part of a first finger, the second surface is partof a second finger, and the third surface is disposed between the firstfinger and the second finger.
 8. The tool of claim 1, further comprisinga slot disposed in the end, wherein the slot forms a shape that iscomplementary to a shape of the rocker arm.
 9. The tool of claim 1,further comprising at least one projection extending away from the baseand capable of at least partially supporting the tool on one or moreengine components.
 10. The tool of claim 1, wherein the base furthercomprises a base extension.
 11. The tool of claim 10, further comprisingat least one rib attached to the base extension and the base.
 12. Thetool of claim 10, further comprising an opening in the base extensionand a grip attached to the base extension near the opening.
 13. A methodcomprising the steps of: inserting one or more rocker arms into one ormore slots of one or more alignment members of an installation tool suchthat the alignment members engage the one or more rocker arms and atleast partially restrain the rocker arms; moving the one or more rockerarms into a desired position with the installation tool; aligning andengaging one or more push rods with the rocker arms; disengaging theinstallation tool from the rocker arms.
 14. The method of claim 13,further comprising the step of resting a support surface of theinstallation tool on an engine component.
 15. The method of claim 13,further comprising the step of engaging one or more valve stems with theone or more rocker arms before the step of disengaging.
 16. The methodof claim 13, wherein the step of disengaging is performed after securinga rocker arm carrier for the one or more rocker arms to an engine block.17. The method of claim 13, further comprising the step of reusing theinstallation tool during assembly of another engine.